A variety of end mills for use with rotating milling cutters are available and well known. Depending on design, such end mills are generally used in right hand cutting, right hand spiral and center cutting. Conventionally, these end mills are made from different types of hardened steel. Standard end mills are supplied in a two or more flute design. A number of end mills have only one operating surface on the cutting face wall. Such end mills often have problems with chips adhering to the cutting face wall and do not achieve a cut as clean as an end mill with two operating surfaces.
U.S. Pat. No. 3,003,224 to Ribich discloses an end mill with two operating surfaces on the cutting face wall, a primary and a secondary tooth surface. This end mill did achieve a cleaner cut and greatly reduced the problems with chips adhering to the cutting face walls.
However, while an improvement over prior end mills, this end mill has several deficiencies and limitations, particularly when used with the high speed machining capabilities of the present state of the art. First, corner wear and chipping edges are a continuing problem. Second, during use, the end mill often creates a loud squeaking noise. Furthermore, the end mill has a limited useful life and can only be used at limited speeds.